ObjectContext.SaveChanges Method ()

 

Persists all updates to the data source and resets change tracking in the object context.

Namespace:   System.Data.Objects
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

Public Function SaveChanges As Integer

Return Value

Type: System.Int32

The number of objects in an Added, Modified, or Deleted state when SaveChanges was called.

Exception Condition
OptimisticConcurrencyException

An optimistic concurrency violation has occurred in the data source.

To ensure that objects on the client have been updated by data source-side logic, you can call the Refresh method with the StoreWins value after you call SaveChanges. For more information, see Saving Changes and Managing Concurrency.

SaveChanges operates within a transaction. SaveChanges will roll back that transaction and throw an exception if any of the dirty ObjectStateEntry objects cannot be persisted.

If an optimistic concurrency violation has occurred, an OptimisticConcurrencyException is thrown. You can resolve an optimistic concurrency violation by catching it, calling the Refresh method with the StoreWins or ClientWins value, and then calling SaveChanges again. For more information, see How to: Manage Data Concurrency in the Object Context.

This example is based on the AdventureWorks Sales Model. This example tries to save changes, which may cause a concurrency conflict. Then, it demonstrates how to resolve the concurrency conflict by refreshing the object context before re-saving changes.

Using context As New AdventureWorksEntities()
    Try
        ' Perform an operation with a high-level of concurrency. 
        ' Change the status of all orders without an approval code. 
        Dim orders As ObjectQuery(Of SalesOrderHeader) = context.SalesOrderHeaders.Where("it.CreditCardApprovalCode IS NULL").Top("100")

        For Each order As SalesOrderHeader In orders
            ' Reset the order status to 4 = Rejected. 
            order.Status = 4
        Next
        Try
            ' Try to save changes, which may cause a conflict. 
            Dim num As Integer = context.SaveChanges()
            Console.WriteLine("No conflicts. " & num.ToString() & " updates saved.")
        Catch generatedExceptionName As OptimisticConcurrencyException
            ' Resolve the concurrency conflict by refreshing the 
            ' object context before re-saving changes. 
            context.Refresh(RefreshMode.ClientWins, orders)

            ' Save changes. 
            context.SaveChanges()
            Console.WriteLine("OptimisticConcurrencyException handled and changes saved")
        End Try

        For Each order As SalesOrderHeader In orders
            Console.WriteLine(("Order ID: " & order.SalesOrderID.ToString() & " Order status: ") + order.Status.ToString())
        Next
    Catch ex As UpdateException
        Console.WriteLine(ex.ToString())
    End Try
End Using

.NET Framework
Available since 3.5
Return to top
Show: